Spectroscopic Studies of Molybdenum and Tungsten Enzymes

过渡金属离子是大量酶的组成部分，催化了许多最具化学挑战性和工业相关的生物反应。在生物所使用的所有金属中，钼和钨被区分为唯一在生物中具有已知功能的第二行和第三行过渡元素；钨被进一步区分为生命中使用的最重的元素。从细菌到植物，再到无脊椎动物和哺乳动物，这些金属在几乎所有生物的酶中都起着功能性作用。它们在酶活性位点内完成这一过程，这些酶活性位点都含有由一种不寻常的含硫辅因子结合的金属。尽管酶在结构上具有共性，但在催化的不同化学反应范围内，酶所扮演的功能角色也同样多样；例如，它们在微生物呼吸、绿色植物吸收氮、控制昆虫眼睛颜色和人类健康方面发挥着重要作用。本文采用同步加速器和计算化学相结合的方法，对钼和钨酶的主要家族进行了系统的研究。我们建议使用一种新颖的整体方法，将x射线吸收光谱信息，先进的计算机分子建模和晶体结构相结合，以获得迄今为止最准确的活性位点图像。这项工作的最终目标是对酶的催化机制进行深入的定量结构和电子理解，比较和对比不同家族之间和内部的酶。这将有助于更好地理解钼酶如何实现其显著的功能多样性。这项研究的好处有三方面：(1)研究结果将为一组重要的酶提供详细的见解(2)所开发的整体方法将广泛适用于所有金属蛋白的研究(3)该研究将加强加拿大在利用结构分子生物学中主要同步加速器工具之一方面的努力。

Transition metal ions are integral parts of a large number of enzymes, catalyzing many of the most chemically challenging and industrially relevant reactions carried out by living organisms. Among all of the metals employed by living things, molybdenum and tungsten are distinguished as being the only second-row and third-row transition elements with a known function in living creatures; tungsten is further distinguished as the heaviest element used in life. The metals have functional roles in enzymes in almost all living creatures, from bacteria through plants to invertebrates and mammals. They do this within enzyme active sites that all contain the metal bound by an unusual sulfur-containing cofactor. Despite commonality in structure, the enzymes are remarkable in the range of different chemical reactions that are catalyzed, and the functional roles filled by the enzymes are equally diverse; for example, they play essential roles in microbial respiration, in the uptake of nitrogen in green plants, in controlling insect eye color, and in human health. The proposed work is a systematic study of the major families of molybdenum and tungsten enzymes using a combination of synchrotron-based and computational chemistry methods. We propose to use a novel holistic approach in combining information from X-ray absorption spectroscopy, advanced computer molecular modeling, and crystal structures to obtain the most accurate picture yet of the active sites. The ultimate goal of the work is to develop an in-depth quantitative structural and electronic understanding of the catalytic mechanisms used by the enzymes, comparing and contrasting between and within the different families. This will lead to an improved understanding of how molybdenum enzymes achieve their remarkable functional diversity. The benefits of this research are three-fold (i) The results will yield detailed insights for an important group of enzymes (ii) The holistic approach developed will be broadly applicable to all metalloprotein studies (iii) The research will strengthen the Canadian effort in utilizing one of the major synchrotron tools in structural molecular biology.